小道具：ホスト名からIPアドレスを得る(getaddrinfo の動作確認)

getaddrinfo の動作確認用です

getaddrinfo を使用して、ホスト名に対しする IP アドレスを表示します。

getaddrinfo.py

#!/usr/bin/env python3

import socket
import argparse


def get_socket_param(name):
    if name in socket.__dict__:
        return socket.__dict__[name]
    return int(name)


def get_socket_name(prefix, value):
    nprefix = len(prefix)
    for key in socket.__dict__:
        if (len(key) > nprefix and
            key[:nprefix] == prefix and
                socket.__dict__[key] == value):
            return key
    return f'{value}'


parser = argparse.ArgumentParser()
parser.add_argument('host')
parser.add_argument('-N', '--port', help='ポート番号を指定')
parser.add_argument('-A', '--family', help='AF_ に続く名前を指定')
parser.add_argument('-T', '--type', help='SOCK_ に続く名前を指定')
parser.add_argument('-P', '--proto', help='IPPROTO_ に続く名前を指定')
parser.add_argument('flag', nargs='*', help='AI_ に続くフラグ名前を指定')
args = parser.parse_args()

host = args.host
port = 0 if not args.port else int(args.port)
af_family = 0 if not args.family else get_socket_param('AF_' + args.family.upper())
sock_type = 0 if not args.type else get_socket_param('SOCK_' + args.type.upper())
ipproto = 0 if not args.proto else get_socket_param('IPPROTO_' + args.proto.upper())
flags = sum(get_socket_param('AI_' + flag.upper()) for flag in (args.flag or []))

param = ', '.join([f'host="{host}"',
                   f'port={port}',
                   'family=%s' % get_socket_name('AF_', af_family),
                   'type=%s' % get_socket_name('SOCK_', sock_type),
                   'proto=%s' % get_socket_name('IPPROTO_', ipproto),
                   f'flags=0x{flags:02x}'])

print(f'getaddrinfo({param}):')
addrinfo = socket.getaddrinfo(host, port, af_family, sock_type, ipproto, flags)
print('\n'.join(ai[4][0] for ai in addrinfo))

実行結果

$ python3 getaddrinfo.py example.com
getaddrinfo(host="example.com", port=0, family=AF_UNSPEC, type=0, proto=IPPROTO_IP, flags=0x00):
2606:2800:220:1:248:1893:25c8:1946
2606:2800:220:1:248:1893:25c8:1946
93.184.216.34
93.184.216.34
$ python3 getaddrinfo.py example.com -A inet
getaddrinfo(host="example.com", port=0, family=AF_INET, type=0, proto=IPPROTO_IP, flags=0x00):
93.184.216.34
93.184.216.34
$ python3 getaddrinfo.py example.com -A inet6
getaddrinfo(host="example.com", port=0, family=AF_INET6, type=0, proto=IPPROTO_IP, flags=0x00):
2606:2800:220:1:248:1893:25c8:1946
2606:2800:220:1:248:1893:25c8:1946